Database results:
examBoard: Cambridge
examType: IGCSE
lessonTitle: Gradient, Contour Lines and Heights
Maps are like a secret code that geographers use to understand the world. In this session, we'll learn how to decode information about the shape of the land - whether it's flat, steep, hilly or mountainous. These skills are essential for fieldwork, understanding landscapes and answering exam questions correctly!
Key Definitions:
Gradient tells us how steep a slope is. It's really useful for understanding landscapes, planning routes and explaining physical processes like erosion or landslides.
Gradient is calculated using this simple formula:
Gradient = Vertical height change ÷ Horizontal distance
The answer can be expressed as:
The steeper the slope, the larger the gradient value.
Imagine hiking from point A (100m above sea level) to point B (150m above sea level). The horizontal distance between them is 1000m.
Vertical height change: 150m - 100m = 50m
Horizontal distance: 1000m
Gradient: 50 ÷ 1000 = 0.05
This can be written as 1:20, 1/20, or 5%
Contour lines are the key to understanding the 3D shape of the land from a 2D map. They connect points of equal height above sea level. By reading contour lines, you can visualise mountains, valleys and slopes.
Basic rules:
Common landforms and their contour patterns:
Hikers, mountain bikers and runners use contour lines to plan routes. A path crossing many contour lines at right angles will be steep and challenging. A path running parallel to contour lines will be relatively flat and easier to travel.
In the Lake District, a popular UK hiking destination, routes are often planned to follow contour lines around mountains rather than going straight up and down, making the journey less strenuous.
Maps show heights in several ways. Understanding these will help you interpret the landscape accurately.
Exact heights marked at specific points on a map, shown as a dot with a number beside it.
Example: •342 means this exact point is 342 metres above sea level.
Marked as a triangle with a dot in the centre, these are concrete pillars on high points used for surveying.
The height is usually shown next to them.
A mark on a fixed object indicating height above sea level.
On OS maps, they're shown as BM 286.5 meaning 286.5 metres above sea level.
A cross-section is like slicing through the landscape to see its profile from the side. It's a brilliant way to visualise the terrain and is a common exam skill.
Follow these steps to create an accurate cross-section from a map:
Top Tip: Always include a vertical exaggeration note if you've used different horizontal and vertical scales. For example: "Vertical exaggeration 5x".
These cartographic skills aren't just for exams - they're used in real-world situations every day!
Understanding gradient helps hikers plan routes and estimate journey times. Steeper gradients require more energy and time to climb.
Mountain rescue teams use contour patterns to identify potential hazard areas and plan rescue routes.
Engineers use gradient calculations when designing roads, railways and drainage systems.
Urban planners consider topography when deciding where to build new developments, avoiding areas prone to flooding or landslides.
In 2015, severe flooding affected Cumbria in northwest England. Geographers and emergency planners used contour maps to:
This real-world application shows how understanding contour lines and gradient can literally save lives!
When working with contour lines and gradients, watch out for these common errors:
In this session, we've learned how to:
These cartographic skills are essential tools for any geographer. They help us understand landscapes, plan fieldwork and analyse how physical processes shape our world. With practice, you'll be reading the landscape like a pro!
Log in to track your progress and mark lessons as complete!
Login NowDon't have an account? Sign up here.